What is Alkalinity and how do you measure it?

“P” All the OH and half of the Carbonate, “T” Total Alkalinity rest of the carbonate and all of the Bicarbonate, OH is calculated 2P – T = OH

• For the P test, add Phenolphthalein to sample, titrate to color change pink to clear. Record P.
• To the same sample add Total Alkalinity indicator. Sample turns green. Titrate to red. Record T.
• OH = 2P-T
• A more accurate OH would be to add BaCl to sample. Add Phenolphthlein. Titrate pink to clear.